A combustion engine exhibits irregularities due to the successive combustion events in the cylinders of the engine, the frequency of the irregularities varying in particular depending on the number of cylinders operating and the rotation speed of the engine. The function of a damping system is to filter, upstream from the gearbox, the vibrations caused by the irregularities. Otherwise the vibrations penetrating into the gearbox would cause particularly undesirable shocks, noise, or acoustic impacts therein during operation.
Damping systems of the pendulum type, also called “pendulum oscillators” or “pendulums,” which are part of motor vehicle transmissions, are known in the existing art.
A vibration damping system of the pendulum type is described in particular in the document FR2981714. This system has pendulum flyweights mounted movably on a support pivoting around an axis. Each pendulum flyweight is mounted on the support by means of a guidance device. The pendulum flyweights are tuned as a function of the number of cylinders in the engine in order to filter the vibrations at an order for which said vibrations, caused by the irregularities of the engine, are most significant.
It has been found that for certain engine speeds, harmonics of an order higher than the order of the preponderant harmonics to be filtered are amplified despite strong damping of the preponderant harmonics.
The document US2014/0102398 furthermore describes a device whose masses and/or inertial masses of the pendulum flyweights are adapted so that the sets of pendulum flyweights do not interfere with each other, but this also degrades the performance of the vibration damping system.